1. Field of the Invention
This invention relates to handles for sporting goods, specifically to tennis racquets.
2. Prior Art
Conventional tennis racquets have an octagonal handle whose longest faces are parallel to the racquet face. A plastic cap is at the butt of the handle, which makes the butt slightly wider than the rest of the handle. Because such a handle shape does not conform to the anatomy of the hand, but is purely arbitrary, the ulnar portion of the hand tends to slip off the end of the handle when the hand becomes wet, which has led to various grip coverings intended to reduce hand slippage.
The center of gravity in a conventional tennis racquet is located near the racquet face rather than near the hand of the player. The racquet is a cantilever. This distant weight, over time, tires the muscles of the player's wrist and forearm and aggravates the aforementioned problem with hand slippage. Moreover, the racquet is not as easy to position during fast play as it might be with the center of gravity closer to the player's hand. Recent improvements in racquet frame design have reduced the weight of the racquet head significantly, but this loss of mass necessarily entails a reduction of possible momentum. These light racquets are less powerful. Moreover, these light racquets transmit more shock from off-center ball impacts to the player's wrist and elbow, leading over time to tendonitis ("tennis elbow").
Despite numerous patented novelties in racquet design, none have succeeded in supplanting the conventional octagonal shape of the handle. Only insignificant adjustments have been made to the conventional location of the racquet's center of gravity. Light, rigid, head-heavy racquets with octagonal handles are the only marketed design.
1. ELLIPSOIDAL HANDLE SHAPE
U.S. Pat. No. 4,183,528 to An (1980), particularly FIG. 10 thereof, shows a partially ellipsoidal handle. The ellipsoidal portion, however, is not meant to engage the crook of the fingers but rather the thenar portion of the hand, as is clear from reference numerals 66a and 66b. The fingers in An's handle crook around an octagonal section.
U.S. Pat. No. 4,470,599 to Usher (1982) shows a racquet handle that is half-round and half-octagonal in cross-section. The round portion is meant to engage the thenar portion of the hand while the fingers crook around the octagonal portion.
U.S. Pat. No. 4,349,199 to Vulcano (1982) shows a non-ellipsoidal handle. However, one side of Vulcano's handle narrows to fit into the crook of the fingers.
U.S. Pat. No. 4,759,546 to Steele (1988), particularly FIGS. 12 and 13 thereof, shows a semi-ellipsoidal handle which in end view has one side round and one side ogive. The apparently ogive portion does not engage the crook of the fingers, however. The projection (100) at the tip of the handle which gives the racquet an ogive end view is meant to prevent longitudinal rather than radial motion of the handle. Cf. Column 10:48-52. The fingers grip a "variable generally octagonal cross-sectional shape." Col. 10:20-21. FIG. 9 illustrates the cross-section of Steele's handle where the fingers engage it, and this cross-section is definitely octagonal. Col. 10:26-31. If there were an actual, rather than merely apparent, ogive portion to Steele's handle, it would engage the crook of the fingers if Steele's handle is gripped in what he calls the "upslope" position. FIGS. 12 and 13. But Steele teaches a "downslope" position for the same handle, as illustrated in FIGS. 14 and 15, where it is the round side of the handle that engages the crook of the fingers. The transverse axis of this semi-ellipsoidal handle is in the plane of the racquet face. Steele's grip is of the offset, or pistol-grip variety.
U.S. Pat. No. 3,374,590 to Strickland (1983) shows a racquet handle having a cross-section consisting of a pair of parallel flat sides joined by arcs. The long axis of said cross-section is in the plane of the racquet face.
U.S. Pat. No. 4,828,261 to Kleylein (1989) discloses a racquet grip which may be of an ellipsoidal cross-section. The orientation of the ellipsoidal major axis to the racquet face is fixed in the plane of the racquet face. Kleylein's mention of an oval cross-section is not integral to his invention, and is only made in passing as an alternative to a circular cross-section. Col. 4:15-17.
2. FLARED HANDLE SHAPE
U.S. Pat. No. 4,549,736 to Lofty (1985) shows a handle which flares in the plane of the racquet face, with the cross-section of the handle rectangular throughout.
U.S. Pat. No. 4,183,528 to An (1980), particularly FIG. 8 thereof, shows an offset, gunstock-type racquet handle flaring in the plane of the racquet face. Only one half of the handle, which is the octagonal part, flares outward from the longitudinal axis of the handle.
U.S. Pat. No. 4,351,529 to Schultz (1980) shows a racquet handle which flares at the butt, outside the hand. Only half of the butt flares. The objective of this improvement is not to provide more security from radial movement but rather from longitudinal movement. Only the heel of the hand engages the flared portion of the handle.
U.S. Pat. No. 4,828,261 to Kleylein (1989) discloses a racquet grip with a "raised-length portion" that fits into the middle of the player's hand.
U.S. Pat. No. 4,438,925 to Lindstrom (1984) shows a racketball racquet handle of octagonal cross-section with a increasing circumference toward the racquet face. The ring and little fingers are to grip tightly around the narrow portion at the bottom of the handle while the forefinger and middle finger grip loosely around the wider portion at the top.
U.S. Pat. No. 4,736,950 to Doyle (1988) shows a racquet handle which, like Lindstrom's, increases in circumference toward the racquet face. Doyle's handle, which is of circular cross-section, tapers linearly from its narrowest circumference at the butt up to its widest circumference at the middle finger.
3. RADIAL ALIGNMENT OF HANDLE
U.S. Pat. No. 3,545,755 to Owada (1970) discloses a racquet with a twist in its throat which gives its handle a permanent radial alignment at a certain angle relative to the plane of the racquet face. Said alignment is not adjustable.
U.S. Pat. No. 4,183,528 to An (1980), particularly FIG. 10 thereof and the discussion at Column 6: 14-58, shows an offset racquet handle with a permanent radial alignment in addition to the offset angle.
U.S. Pat. No. 4,854,596 to Carbonetti (1989) discloses a handle which is radially adjustable during play.
4. WEIGHT IN HANDLE
U.S. Pat. No. 4,690,405 to Frolow (1987), discloses a racquet with a weight located inside its handle. This improvement to Frowlow's prior patented racquet (U.S. Pat. No. 4,165,071) was necessary because the light weight and high rigidity of Frolow's earlier invention are contrary to accepted principles of vibration reduction. The magnitude of this handle weight is only approximately 0.15 of the total weight of the racquet, and the overall weight of Frolow's racquet remains very light, approximately 330 grams. Frowlow's addition of a weight means is only for the purpose of vibration damping, not for greater power or control. Frolow's weight is located inside, and not distal to, the player's hand. This fact is not clear from Frolow's disclosure, but from his claims. In all claims relating to the weight means in his invention, whether dynamic or static, Frolow specifies that the center of gravity of the weight means is located a distance from the butt end of the handle less than 0.26 of the total length of the racquet. The center of gravity in Frolow's racquet remains close to the head, which Frolow considers to be an advantage. Col. 4: 36-41.
U.S. Pat. No. 3,941,380 to Lacoste (1976) shows a dynamic weight attached to an elastic element inside the handle for the purpose of vibration damping.
U.S. Pat. No. 4,203,596 to Nagamoto (1980) shows plates inside a racquet handle. The magnitude of this static weight is between 20 and 30 grams.
5. VIBRATION-DAMPING MEANS IN HANDLE
U.S. Pat. No. 4,690,405 to Frolow (1987), discloses a racquet with vibration damping characteristics due to a weight means located inside its handle. This improvement to Frolow's prior patented racquet (U.S. Pat. No. 4,165,072) was necessary because the light weight and high rigidity of Frolow's earlier invention are contrary to accepted principles of vibration reduction. The amount of this handle weight is relatively small in relation to the weight of the racquet, approximately 0.15 of the total weight, and the overall racquet weight of Frolow's racquet remains very light. The center of gravity of Frolow's racquet remains far away from the handle. Frolow considers this location of the center of gravity to be an advantage for vibration damping inasmuch as--according to Frowlo--"the further away the forces at the handle end from the fulcrum, the smaller these forces need to be to balance the forces being generated on the other end of the fulcrum, namely the shock and vibratory forces generated by the impact of the ball upon the racket." Col. 4: 36-41.
U.S. Pat. No. 3,941,380 to Lacoste (1976) shows a dynamic weight attached to an elastic element inside the handle for the purpose of vibration damping.
U.S. Pat. No. 4,105,205 to Theodores (1978) shows a vibration-damping fluid cavity within a racquet handle.
6. CENTER OF PERCUSSION SHIFTING MEANS
U.S. Pat. No. 4,165,071 to Frolow (1979) discloses a very light and extremely stiff racquet whose center of gravity is farther from the handle than in prior art. Frolow assumes a pivot located at the end of the handle rather than where it really is, at the hand, and claims an increase in the distance of the center of percussion from the handle due to lightening of the handle relative to the racquet face.
U.S. Pat. No. 4,355,803 to Rama (1982) shows a racquet with a moveable weight located between the hand and the racquet face.
U.S. Pat. No. 3,833,219 to Dean (1974) shows a racquet whose center of gravity is adjusted by varying the length of the racquet.
U.S. Pat. No. 4,732,384 to Seymour (1988) shows a racquet with an adjustable weight at its throat in order to broaden the "sweet spot" of the racquet by shifting the center of gravity to a point at the center of its length.